Matrox Iris GT MIL, Installation And Technical Reference, Page: 113 / 256

Connecting external devices to auxiliary output signals 113
Connecting to a TTL device
To connect your Matrox Iris GT to a TTL device, you must first connect an
external pull-up resistor between them. The external pull-up resistor is needed
because TTL devices expect to be connected to a device that can provide power
(a sourcing device) and your Matrox Iris GT is a sinking device.
Connect an auxiliary output signal of your Matrox Iris GT and the device input
to an external pull-up resistor. In addition, connect the ground of the TTL device
and the ground of your Matrox Iris GT to a common ground.
The external pull-up resistor assures that when the output is disabled (off ), the
external resistor will pull-up the device’s input to a positive voltage (+V).
Therefore, the device input is "on" when your Matrox Iris GT output is "off",
and vice-versa.
In 0
GND
Matrox Iris GT digital I/O
and power connector
TTL device
GND
External
pull-up
resistor
Power
source
+5V
AUX(USER)_OPENC_OUT0
1
1
Note that the output can
sink up to 100 mA.